Yesterday was one of the most interesting days we've had this semester by far!
In the medical physiology class we have a live animal lab in which a live anesthetized pig is used to demonstrate what happens when given certain hormones through a catheters. We gave a variety of injectable hormones to see how hormones these effect the heart rate and blood pressure. We monitored the arterial blood pressure using femoral artery catheters that we inserted ourselves. To do this we had to cut open the thigh area, find the femoral arteries, and cut tiny holes in them to insert plastic catheter tubes. We also exposed the carotid arteries in the neck to test what would happen to blood pressure when the carotids are occluded.
The hormones we gave were epinephrine (this is the same hormone that would be in an "epi" pen) and norepinephrine and acetylcholine. All these hormones have a variety of effects on heart rate and blood pressure and differ at varying dosages. Some made the heart rate RACE up to almost 200 beats per minute while others didn't affect the heart rate much at all. Some of the hormones made the blood pressure SPIKE.
The lab got super interesting when we opened the chest cavity. I cut open the pig on its side in between the ribs bones and through the rib muscle until you could get a tiny view of the lungs. Then we used a metal retractor to spread the rib bones apart to get a better view inside. You could see the bright pink lungs inhaling and exhaling and after removing the pericardium you could see the heart pumping away. It is amazing how much movement is going on inside your chest. Believe me this heart was moving all over the place and pumping hard. It is phenomenal to think this heart beats ~72 beats per min, 24 hours a day, 52 weeks a year, for ~74.6 years (on average). AMAZING.
As part of the lab exercise we caused the heart to go into fibrillation (this is when the heart is not pumping but just quivering and needs to be defibrillated AKA "shocked" with paddles). So after the heart went into fibrillation we defibrillated the heart with internal paddles and tried to get the heart going again. We didn't get the heart pumping with the defibrillator so we tried cardiac message which is using your hand to pump the heart and get blood moving around. After cardiac message you try to defibrillate again to get the heart to beat on its on-- this didn't work either. So our pig's heart beat didn't come back which unfortunately happens a lot when trying to bring a heart back after it goes into fibrillation. Our professor said the heart was probably more difficult to bring back because the pig had be under anesthesia for almost 5 hours at that time.
A couple years ago PETA through a fit when they heard about this lab and I can understand how they would not appreciate us using live animals to practice these surgical techniques. However, I assure you it is far better for med student to practice on anesthetized animals than on someone's relative, friend, child, spouse, ect. These animals provide a purposeful and meaningful experience and help us to be better physicians later on. Believe me all of us appreciated the experience and I can say for myself it was one of the highlights of the semester thus far. Every time you check your heart rate or feel your chest and feel the beating just know that heart is working hard for you! And on a side note: this pig had MUCH prettier lungs than my cadaver had--this pig didn't smoke :) Keep your lungs pretty in pink!
Thanks for reading!
Salt and Light,
Kelly
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